Non-woven roll towel material

ABSTRACT

A NON-WOVEN ROLL TOWEL MATERIAL INCLUDING A CENTRAL LAYER OF AN OPEN MESH CROSSED THREAD FABRIC COMPRISING RESILIENT WARP THREADS EXTENDING IN THE MACHINE DIRECTION, AND SUBSTANTIALLY NON-RESILIENT FILL THREADS EXTENDING IN THE TRANSVERSE DIRECTION. THE THREAD COUNT IS IN THE RANGE OF FROM ABOUT 1.5 TO ABOUT 5 THREADS PER INCH IN BOTH DIRECTIONS. A MULTI-PLY LAYER OF CELLULOSIC TISSUE IS BONDED TO EACH OF THE OPPOSITE FACES OF THE CENTRAL LAYER, AND THE RESULTING COMPOSITE MATERIAL IS HEAVILY EMBOSSED. THE PREFERRED EMBOSSING TECHNIQUE COMPRISES PASSING A WEB OF THE COMPOSITE MATERIAL THROUGH TWO OR MORE EMBOSSING STATIONS ON THE SURFACE OF A SINGLE EMBOSSING ROLL, AND DRAWING THE WEB AWAY FROM THE SURFACE OF THE EMBOSSING ROLL BETWEEN SUCCESSIVE STATIONS. THIS TECHNIQUE PRODUCES TWO OR MORE EMBOSSMENT REPEATED CONTINUOUSLY ALONG THE LENGTH OF THE COMPOSITE MATERIAL AND OUT OF REGISTER WITH EACH OTHER.

G. D. THOMAS F-TAL NON-WOVEN ROLL TOWEL MATERIAL Original Filed Dec. 23,1968 Jan. 2, 1973 United States Patent C) Int. Cl. B32b 5/12 U.S. Cl.161-57 6 Claims ABSTRACT OF THE DISCLOSURE A non-woven roll towelmaterial including a central layer of an open mesh crossed thread fabriccomprising resilient warp threads extending in the machine direction,and substantially non-resilient fill threads extending in the transversedirection. The thread count is in the range of from about 1.5 to about 5threads per inch in both directions. A multi-ply layer of cellulosictissue is bonded to each of the opposite faces of the central layer, andthe resulting composite material is heavily embossed. The preferredembossing technique comprises passing a web of the composite materialthrough two or more embossing stations on the surface of a singleembossing roll, and drawing the web away from the surface of theembossing roll between successive stations. This technique produces twoor more embossments repeated continuously along the length of thecomposite material and out of register with each other.

CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation of our copending application Ser. No. 786,270, filed Dec.23, 1968, now abandoned, and entitled Non-Woven Roll Towel Material andMethod of Producing the Same.

The present invention relates generally to roll towels of the type usedin kitchens and the like and, more particularly, to an improvednon-woven roll towel material.

It is a primary object of the present invention to provide an improvednon-woven roll towel material having an improved combination ofstrength, softness, absorbency, and other desirable characteristics.

Another object of the invention is to provide an improved non-woven rolltowel material of the foregoing type which can be efficiently producedat a relatively low cost.

Still another object of the invention is to provide a method ofproducing an improved non-woven roll towel material of the typedescribed above.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings, in which:

FIG. 1 is a schematic plan view of a composite roll towel materialembodying the invention, with fragments of successive layers broken awayto show underlying layers of the composite material.

FIG. 2 is a partially schematic end elevation of an embossing method andapparatus used in the production of the composite roll towel materialshown in FIG. 1; and

FIG. 3 is a schematic plan view of an embossed flexible web formed bythe method and apparatus illustrated in FIG. 2.

While the invention is susceptible of various modifications andalternative forms, certain specific embodiments thereof have been shownby way of example in the drawings which will be described in detailherein. It should be understood, however, that it is not intended tolimit 3,708,383 Patented Jan. 2, 1973 the invention to the particularforms disclosed but, on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention.

Referring now more particularly to the accompanying drawings, theinvention is embodied in a roll towel material represented in FIG. 1,and including a central layer 10 of non-woven fabric made of open meshcross-laid and bonded threads. More particularly, the fabric layer 10comprises a set of spaced warp threads 11 extending in the machinedirection and a set of spaced fill threads 12 which extend across thewarp threads 11 in the transverse direction. Since the fabric isnon-woven, the fill threads 21 are all on the same side of the warpthreads 20, with the two sets of threads disposed in face-to-facerelation to each other and adhesively bonded together where the threadsof one set cross the threads of the other set. Nonwoven fabrics of thistype are well known in the art, and may be made by any of severaldifferent known methods and apparatus, one example of which is describedin U.S. Pat. No. 2,841,202 to H. W. Hirschy. The threads in each of thetwo cross-laid sets normally run parallel to each other and areuniformly spaced, but the fabric may be formed with the threadsfollowing non-parallel or irregular patterns if desired, as long as oneset of threads is disposed entirely on one side of the other set. Itwill be understood that the term threads is intended to include bothmonofilament and multifilament structures, although multifilamentstructures are generally preferred in non-woven fabrics.

In accordance with one aspect of the present invention, the warp threads11 are made of a resilient material, the fill threads 12 are made of astretchable non-resilient material, and the fabric 10 has a relativelylow thread count in the range of 1.5 to 5 threads per inch, preferably 2to 3 threads per inch, in both directions. The resilient nature of thewarp threads 11 enhances the yieldability of the material for bulkimprovement, without destroying the thread strength, during theembossing operation to be described below. A particularly suitable warpthread is 40 denier high tenacity nylon, which is not only resilient,but also provides an optimum strength-cost characteristic.

It is critical in the present invention that the fill threads 12 besubstantially non-resilient in the final product, in orderto avoidshrinkage of the composite towel material in the transverse directionafter the material is embossed for bulk improvement as described below.More particularly, it has been found that there is a certain amount ofdelayed recovery in resilient threads that causes the roll towel toshrink during storage so that the core on which the towel is woundprotrudes beyond the end of the towel roll. Even where a resilientmaterial is allowed to return or spring back toward its original shapebetween the embossing and winding operations, there is a suflicientamount of delayed recovery to cause core protrusion within about twoweeks after winding. This core protrusion, even if it is only or less,causes shelf stacking problems and is also undesirable from an aestheticstandpoint.

Of course, the fill threads 12 must be somewhat stretchable to permitthe desired embossing of the composite towel material, but it isimportant that the threads be substantially non-resilient after theembossing operation. That is, the threads 12 must be stretched beyondtheir elastic limit during the embossing operation so that the threadexhibit substantially no resiliency in the final embossed product. Boththe fill threads and warp threads should also have a relatively high wetstrength since the final product is to be used as a towel. Aparticularly suitable material that possesses the particular combinationof properties required for the fill threads 12 is denier rayon, althoughcertain other materials such as polyesters and the like may be selectedwith similar properties. The preferred 125 denier rayon has a relativelylow level of stretch (10-15%), a relatively low elastic limit which iseasily exceeded by the stresses applied to the threads during theembossing operation to render the threads substantially non-resilient,and a strength about equivalent to that of the 40 denier high tenacitynylon that is preferred for the warp threads.

Bonded to the opposite faces of the central layer 10 of non-woven fabricare two outside layers 13 and 14 of cellulosic tissue, with each layer13 and 14 preferably comprising one to four plies of creped cellulosictissue. In the preferred embodiment illustrated in the drawings, eachlayer 13 and 14 is formed of two plies 13a, 13b and 14a, 14b,respectively, of creped cellulosic tissue. The cellulosic tissue ispreferably wet strength treated with a dry basis weight before crepingof from about to about 13 pounds per 2,880 square foot ream, a Frazierporosity between about 45 and about 100, a stretch between about 20% andabout 100%, and a crepe ratio before stretching and pressing of fromabout 1.1 to about 2.5 as it is creped off the dryer of the papermachine. The creped tissue is typically stretched and pressed aftercreping to reduce the original high crepe ratio to about 1.1 to 1.8 inorder to produce a soft sheet such as is customarily used in themanufacture of facial tissue. A particularly preferred cellulosic tissuefor use in the illustrative embodiment of the invention is a crepedtissue having the following characteristics:

(1) Dry basis Weight: 7.6 lbs./ 2880 sq. ft./ ply.

(2) Frazier porosity: 60 and above (CFM at /2 water pressure drop-4ply).

(3) Tensile strength: Machine direction dry-1100:200 gms. (gms./3"/ply).Cross direction dry-600x100 gms. (4) Stretch: 25-35%.

The above tissue permits good ply attachment to be obtained with theno-woven fabric using two conventional silicone calender rolls. Ingeneral, the calendering pressure required increases for creped tissueof lower porosity, higher weight, and higher strength, and increasedfluidity of the fill adhesive at the calender nip may also be desirable.

The bonding of the two layers 13 and 14 of cellulosic tissue to thecentral fabric layer is effected by adhesive that is originally appliedto only the fabric layer, in the illustrative embodiment. This adhesiveis applied to both sets of threads 11 and 12 in order to achieve themost elfective bonding of the warp and fill threads 11 and 12 to eachother and to the tissue layers 13 and 14; the warp thread adhesive isprimarily responsible for bonding the warp threads to the fill threadsduring production of the fabric layer 10, while the fill adhesive isprimarily responsible for bonding the fill threads to the tissue layers13 and 14 to prevent grinning (i.e., rupture of the tissue in thetransverse direction before thread breakage). With the preferredmaterials described above, using two plies of cellulosic tissue on eachside of the central fabric, the warp thread adhesive is applied at arate of 1.2 to 1.5 gms./sq. yd., and the fill adhesive is applied at arate of 4.0 to 6.0 gms./sq. yd. If a greater number of tissue plies areused, they may be interbonded by adhesive applied to a sufiicient areaof adjacent surfaces of the multiple plies to hold them together duringuse; in this case, the adhesive should be applied in a discontinuouspattern so that the desired interbonding is achieved with a minimum ofadhesive and without reducing the flexibility of the composite material.In any event, the particular adhesive or adhesives employed throughoutthe towel material should always be insoluble in water and any otherliquids that might beabsorbed in the towel during use.

While various adhesives may be employed, advantages reside in the use ofplastisols which, as is well known, are colloidal dispersions ofsynthetic resins in a suitable organic ester plasticizer. While manyadhesives of this nature are known those found particularly useful forincorporation in the product of this invention include vinyl chloridepolymers, and copolymers of vinyl chloride with other vinyl resins,plasticized by organic phthalates, sebacates, or adipates. Thesecombinations provide a fast curing plastisol adhesive characterized byrelatively low viscosity, low migration tendencies, and minimumvolatility. Such adhesives remain soft and flexible after curing, can bereactivated by the application of heat and pressure, such as byhot-calendering, and insure that the resultant laminated product retainsthe desired softness, and proper hand and feel. Although plastisols arepreferred, polyvinyl resins per se, plasticized or unplasticized, suchas polyvinyl acetate and copolymers may also be used. Other flexibleadhesive may also be used, including acrylic resins such as the alkylacrylates, and butadiene resins such as butadiene-styrene and butadieneacrylonitriles.

It has been found that the particular combination of materials embodiedin the composite laminate of FIG. 1 is superbly suited for use as a rolltowel, particularly when embossed by the procedure to be describedbelow. Thus, when made with the preferred materials mentioned above anda 3 x 2.5 thread count (number of warp threads per inch x number of fillthreads per inch) in the non-woven fabric 10, a composite roll towel wasproduced with the following characteristics:

(1) Tissue plies 4 .(2) Sheets/roll (11" sheets) 65 (3) Roll diameter,inches 5 (4) Finished basis wt. lbs/2880 sq. ft 42.0 (5) Bulk, inches(10 sheets) 0.4600.470 (6) Absorbent capacity (gms. water per 4" x 4")4.4-4.9 (7) Tensile strength (gms./3"):

Machine direction dry 6600 Cross direction dry 3450 Machine directionwet 2850 Cross direction wet 1300 As can be seen from the above testdata, the improved roll towel provided by this invention exhibitsimproved strength, absorbency, bulk, and roll diameter, particularlywhen compared with other roll towels presently on the market. Moreover,the combination of the multiple plies of the relatively light-weightcellulosic tissue and the reinforcing fabric provides improved tearstrength, softness,

and limpness and is more aesthetically pleasing for roll towel use.

To provide the composite material with the high bulk and texture desiredin a roll towel, it is heavily embossed, preferably by the techniqueillustrated in FIGS. 2 and 3, so that a substantial portion of thecellulosic tissue in each of the multi-ply layers 13 and 14 protrudesthrough the windows of the open mesh fabric 10 and beyond the oppositeface thereof. More particularly, a continuous web 20 of the previouslyformed flexible laminate is drawn around an inlet roller 21 andcontinuously advanced under a guide roll 21:: into engagement with adriven embossing roll 22 at a first embossing station Where the web ispressed firmly against the surface of the embossing roll to form a firstembossment in the web. That is, the web 20 is drawn through the nipformed by the metal embossing roll 22 and a first rubber roll 23 so asto form a first series of repetitive embossments along the length of theweb 20. As can be seen in FIG. 2, the guide roll 21a is located to feedthe web 20 into the nip of the rolls 22 and 23 along a common tangentline for the two rolls. The embossments formed at this first embossingstation are illustrated schematically in FIG. 3 as embossments Arepeated continuously along the length of the web 20. The repetitionrate of the embossments A may be varied by a number of factors,including the diameter of the embossing roll 22 and the rate ofrepetition, if any, of the embossing pattern on the surface of the roll22. For example, if the pattern of the embossing surface on the roll 22repeats itself every ten inches around the circumference of the roll 22,then the length of each embossment A illustrated in FIG. -2 will also beten inches, i.e., the embossments A will be repeated every ten inchescontinuously along the length of the web 20.

As the embossed web is continuously withdrawn from the first embossingstation, it is drawn away from the surface of the embossing roll, andthen passed through a second embossing station on the surface of thesame embossing roll used to form the embossments at the first station.More particularly, the embossed web 20 is continuously withdrawn fromthe nip of the rolls 22 and 23 and drawn away from the surface of theembossing roll 22 over a guide roll 24a. From the guide roll 24a, theembossed web is returned to the surface of the driven embossing roll 22over a second guide roll 24b, and passed through a second embossingstation formed by the nip of the metal embossing roll 22 and a secondrubber roll 25. As can be seen in FIG. 2, the second guide roll 24b islocated to feed the web 20 into the nip of the rolls 22 and 25 on acommon tangent line for the two rolls. As the web is passed through thenip of the rolls 22 and 25, it is again pressed firmly against thesurface of the roll 22 to form a second embossment in the web. Thesesecond embossments are illustrated schematically in FIG. 3 asembossments B repeated continuously along the length of the web 20, withthe repetition rate being determined by the same factors discussed abovein connection with the first embossments A.

It is preferred that the embossments formed at the second embossingstation be out of register with the embossments for-med at the firstembossing station, so that the maximum area of the web is embossed, andto avoid overstressing any given portion of the web material.Consequently, if the embossing pattern on the surface of the metal roll22 repeats itself around the circumference of the roll 22, the locationsof the rubber rolls 23 and 25, the rate of advancement of the web 20,and the distance that the web 20 is drawn away from the surface of roll22 by the guide rolls 24a and 24b must be selected so that theembossments formed at the successive embossing stations are out ofregister with each other. In one example of the illustrative apparatus,the embossing roll 22 has a diameter of 20 inches with an embossingpattern that repeats itself every ten inches around the circumference ofthe roll; the embossing roll 22 is driven at a rate suflicient toprovide a web speed of 500 feet per minute; the embossing stations arelocated at the angular positions shown in FIG. 1; and the centers of theguide rolls 24a and 24b are located 36 and 28 inches, respectively, fromthe center of the driven embossing roll 22.

It will be understood that any desired number of additional embossingstations may be provided around the circumference of the embossing roll22, depending upon the characteristics desired in the final embossedweb. Thus, in the illustrative system, a third embossing station isprovided by a third rubber roll 26 hearing against the outer surface ofthe roll 22. As the double-embossed web 20 emerges from the nip of thesecond rubber roll 25 and the embossing roll 22, the web is drawnoutwardly away from the surface of the embossing roll 22 and over aguide roll 27a. From the guide roll 27a the double-embossed web isreturned under a second guide roll 27b to the surface of the roll 22,and then passed through the third embossing station formed by the nip ofthe third rubber roll 26 and the metal embossing roll 22. As in the caseof guide rolls 21a and 24b described previously, the second guide roll27b is positioned so that the web 20 is fed into the nip of the rolls 26and 22 on a common tangent line for the two rolls.

tAs the web is passed through the nip of the rolls 26 and 22, it is onceagain pressed firmly against the surface of the metal roll 22 to form athird embossment in the web. These third embossments are illustratedschematically in FIG. 2 as embossments C repeated continuously along thelength of the web 20, with the repetition rate being determined by thesame factors discussed above in connection with embossment A. It isagain important that the embossments C be out of register with theembossments A and B, and in the particular example described previouslythe centers of the guide rolls 27a and 27b are located 63 and 32 inches,respectively, from the center of the embossing roll 22. The resultingtripleembossed web emerging from the nip of the rolls 26 and 22 iswithdrawn from the embossing machine as at 30 for winding or furtherprocessing.

In order to maintain the rubber rollers 23, and 26 at a temperaturesufficiently low to prevent degradation of the rubber, the rollers arepreferably water cooled. In general, it is desirable to prevent thetemperature from rising above about 200 F. at any point in the rubber,which is generally in the form of a cover on the outer surface of ahollow metal drum. To facilitate cooling, the rubber cover is typicallymade as thin and hard as possible, consistent with good embossingperformance. As mentioned previously, it is important that the embossingpressure be sufiicient to stretch the fill threads 12 beyond theirelastic limit so that the threads are permanently stressed, whereas theresilient warp threads 11 tend to spring back to their originaldimensions and configuration as soon as the embossing pressure isreleased. Consequently, a substantially constant web length ismaintained between successive embossing stations. Without the resilientwarp threads 11 extending continuously in the machine direction in theweb, the web continuously acquires a permanent stretch at each embossingstation, so that the web length between each pair of successiveembossing stations gradually increases.

(Thus, while it is important to provide non-resilient fill threads toavoid core protrusion, as described previously, it is equally important,when using the illustrative embossing technique, to provide resilientwarp threads to prevent any permanent elongation of the laminated web atany given embossing station so that a substantially constant web lengthis maintained between successive embossing stations.

One of the significant advantages of the illustrative embossingtechnique is that the flexible web may be embossed to any desired degreeby using a single embossing roll, and yet the embossing pressurerequired at each embossing station may be suificiently low to provide along operating life for the embossing equipment, particularly the rolls23, 25 and 26 which are conventionally made of rubber, and whichcooperate with the metal embossing roll to form the embossing stations.For example, if the same degree of embossing attainable with thethree-station arrangement shown in FIG. 1 were to be achieved with asingle embossing station, the embossing pressure required would be sogreat that the risk of failure of the rubber roll from heat build-upwould render the operation unfeasiblc. Furthermore, supplementaloperations such as pin embossing and the like are not necessary toimprove the response of the flexible web to the main embossingoperation, because the desired yieldability, bulk, and embossingresponse is improved in each subsequent embossing station, and it issimply a matter of providing the necessary number of such stationsaround the single embossing roll.

As the toweling is wound on cores after withdrawal from the embossingmachine at 30, transverse tear lines are formed by repetitivelyperforating the toweling at suitable intervals with knives which areclosely enough spaced to at least partially cut substantially all thewarp threads. For example, the toweling may be perforated every 11inches with knives having cutting areas separated by 0.010 spaces, toform corresponding bonds in the toweling. With the exemplary threadcounts mentioned previously, the 0.010" bonds eliminate completely uncutwarp threads or thread hang-ups which cause poor dispensing from theroll during use. To prevent loose cores due to shock absorption duringhandling or shipment, the toweling is preferably wound on cores having asemi-permanent or a permanently dry bond pick-up adhesive on the surfacethereof.

We claim as our invention:

1. An improved non-woven roll towel material comprising the combinationof a central layer of non-woven fabric made of open-mesh cross-laid andbonded threads including stretchable and resilient Warp threads spacedfrom one another and extending in the machine direction and fill threadsspaced from one another and extending in the transverse direction, saidnon-woven fabric having a thread count of from about 1.5 to aboutthreads per inch in both the machine and transverse directions, and alayer of cellulosic tissue bonded to each of the opposite faces of saidcentral layer of non-woven fabric, the composite material formed by saidfabric layer and said cellulosic tissue layers being heavily embossed sothat a substantial portion of the cellulosic tissue in each of saidlayers protrudes through said open mesh fabric and beyond the oppositeface thereof, the resulting heavily embossed composite material beingwound on a core, and said fill threads being substantially non-resilientin the final heavily embossed composite material wound on said core sothat the transverse dimension of said embossed material remains stableduring prolonged storage to prevent transverse shrinkage of saidmaterial and resulting core protrusion.

2. An improved non-woven roll towel material as set forth in claim 1wherein said warp threads comprise high tenacity nylon threads of about40 denier.

3. An improved non-woven roll towel material as set forth in claim 1wherein said fill threads comprise rayon threads of about 125 denier.

4. An improved non-woven roll towel material as set forth in claim 1wherein each of said layers of cellulosic tisue comprises 1 to 4 pliesof cellulosic tissue having a dry basis weight between about 5 and about13 pounds per 8 2880 square feet, a Frazier porosity between about andabout 100, and a stretch between about 20% and about 5. An improvednon-woven roll towel material as set forth in claim 1 which has two ormore embossments repeated continuously along the length of the materialand out of register with each other.

6. An improved non-woven roll towel material comprising the combinationof a pair of flexible layers of non-woven absorbent material, each ofsaid layers including at least one ply of creped cellulosic tissue, andan open-mesh, non-woven web of crossed threads interposed between saidlayers with said threads being bonded to each other at their crossingsand said flexible layers being bonded to the threads which extend in atleast one direction, said web comprising stretchable and resilient warpthreads spaced from one another and extending in the machine directionand fill threads spaced from one another and extending in the transversedirection, the thread count of both said warp threads and said fillthreads being from about 1.5 to about 5 threads per inch, the compositematerial formed by said web of crossed threads and said layers ofabsorbent material being heavily embossed so that a substantial portionof the cellulosic tissue in each of said layers protrudes through saidopen mesh fabric and beyond the opposite face thereof, the resultingheavily embossed composite material being wound on a core, and said fillthreads being substantially non-resilient in the final heavily embossedcomposite material wound on said core so that the transverse dimensionof said embossed material remains stable during prolonged storage toprevent transverse shrinkage' of said material and resulting coreprotrusion.

References Cited UNITED STATES PATENTS 3,546,056 12/1970 Thomas 16157WILLIAM A. POWELL, Primary Examiner US. Cl. X.R.

